Embodiments of the present invention generally relate to equipment and methods for coupling a top drive to one or more tools. The coupling may transfer both axial load and torque bi-directionally from the top drive to the one or more tools.
A wellbore is formed to access hydrocarbon-bearing formations (e.g., crude oil and/or natural gas) or for geothermal power generation by the use of drilling. Drilling is accomplished by utilizing a drill bit that is mounted on the end of a tool string. To drill within the wellbore to a predetermined depth, the tool string is often rotated by a top drive on a drilling rig. After drilling to a predetermined depth, the tool string and drill bit are removed, and a string of casing is lowered into the wellbore. Well construction and completion operations may then be conducted.
During drilling and well construction/completion, various tools are used which have to be attached to the top drive. The process of changing tools is very time consuming and dangerous, requiring personnel to work at heights. The attachments between the tools and the top drive typically include mechanical, electrical, optical, hydraulic, and/or pneumatic connections, conveying torque, load, data, signals, and/or power.
Typically, sections of a tool string are connected together with threaded connections. Such threaded connections are capable of transferring load. Right-hand (RH) threaded connections are also capable of transferring RH torque. However, application of left-hand (LH) torque to a tool string with RH threaded connections (and vice versa) risks breaking the string. Methods have been employed to obtain bi-directional torque holding capabilities for connections. Some examples of these bi-directional setting devices include thread locking mechanisms for saver subs, hydraulic locking rings, set screws, jam nuts, lock washers, keys, cross/thru-bolting, lock wires, clutches and thread locking compounds. However, these solutions have shortcomings. For example, many of the methods used to obtain bi-directional torque capabilities are limited by friction between component surfaces or compounds that typically result in a relative low torque resistant connection. Locking rings may provide only limited torque resistance, and it may be difficult to fully monitor any problem due to limited accessibility and location. For applications that require high bi-directional torque capabilities, only positive locking methods such as keys, clutches or cross/through-bolting are typically effective. Further, some high bi-directional torque connections require both turning and milling operations to manufacture, which increase the cost of the connection over just a turning operation required to manufacture a simple male-to-female threaded connection. Some high bi-directional torque connections also require significant additional components as compared to a simple male-to-female threaded connection, which adds to the cost.
Safer, faster, more reliable, and more efficient connections that are capable of conveying load, data, signals, power and/or bi-directional torque between the tool string and the top drive are needed.